The present invention relates to a dielectric mirror for reflecting laser radiation away from a portion of an apparatus. For example, the dielectric mirror may be included in a slider overcoat to help reduce damage to the slider during a laser bonding process for electrically connecting bond pads of the slider to interconnect traces of a gimbal and actuator arm of a disc drive suspension assembly.
A magnetic read/write head (“magnetic transducer”) of a magnetic data storage and retrieval system is typically fabricated in a large array of identical devices on a surface of a ceramic wafer. The finished array of magnetic transducers is embedded in a layer of an insulating material, which is often called an insulating layer or an overcoat. A hard, transparent aluminum oxide material is often used as the insulating material. The wafer is cut and machined to create thousands of magnetic transducers. The ceramic block associated with each magnetic transducer is often called a slider. In addition to a magnetic transducer, the slider often has bond pads (also known as “electrical contact pads”), where the bond pads are used to electrically connect the magnetic transducer to read and write circuitry of a disc drive.
Air bearing sliders have been extensively used in disc drives to position a magnetic transducer above a rotating disc. Conventionally, head positioning is accomplished by operating an actuator arm with a large-scale actuation motor, such as a voice coil motor (“VCM”), to radially position the slider over a track on the disc. A typical disc drive system may include a suspension assembly attached to the actuator arm for supporting and positioning the slider. The suspension assembly includes a load beam attached to the actuator arm and a gimbal disposed at an opposite end of the load beam. This type of suspension assembly may be used with both magnetic and nonmagnetic discs. The slider may then be attached to the gimbal and actuator arm to form a head gimbal assembly (“HGA”). The VCM rotates the actuator arm and the suspension assembly to position the magnetic transducer over a desired radial track of the disc.
In order for the disc drive to read and write data from the magnetic transducer, read and write circuitry of the disc drive must be able to communicate with the slider. Typically, the HGA serves to electrically connect the magnetic transducer to an electronics module within the disc drive. Interconnect traces, which may be located on a flexible printed circuit or formed directly on the gimbal and actuator arm, are electrically connected to bond pads of a slider. Difficulties may arise in making the electrical connection because a heat source used in the connection process may cause damage to the slider.
Thermal interconnect (“TIC”) bonding can be used to connect a slider bond pad to its respective HGA interconnect trace. In TIC bonding, a ball of molten solder is ejected from a capillary on a trajectory that intercepts an intended point of attachment between the slider bond pad and its respective HGA interconnect trace. An infrared laser operating at a wavelength of approximately 1.08 micrometers (μm) may be used as a heating source for the TIC bonding process. If a laser is used, the laser beam is directed at a 45 degree angle to the bond pad surface of the slider and the interconnect trace. Ideally, the laser beam irradiates only the solder and the bond pad and interconnect trace surfaces. In practice, however, the laser beam irradiates areas of the slider bond pad surface that are not covered by a bond pad (“incident radiation”). As a result, the slider may absorb incident laser radiation, which may then cause damage to the slider.
Similar problems may arise when a portion of an apparatus requires exposure to laser radiation while another portion of an apparatus may be damaged by the laser radiation.